Applicant is not aware of any published material related to the use of optical fiber (in any way) in a solar energy converter. After an extensive literature search in December 2007, Applicant was able to find one paper proposing frequency conversion in a thin-film layer on top of a photovoltaic [Richards and Shalav, Synthetic Metals, 154 (2005) 61-64]. The approach described in the found literature is limited to almost single-pass conversion efficiency although some guiding can happen in a layer and it wouldn't have the many other advantages that fiber offers including thermal management, realm of super high concentration, etc. to name a few.
A primary objective of the present invention is to provide methods and systems to increase the efficiency of a photovoltaic (PV) via optical filtering and concentration of the incident sunlight (or radiation from any other directed electromagnetic energy source).
A secondary objective of the present invention is to provide methods and systems to frequency convert the filtered energy so that it's within the response range for photovoltaic conversion.
A third objective of the present invention is to provide methods and systems to achieve the optical filtering and/or frequency conversion in conjunction with a solar thermal loop into which out-of-band energy is directed via radiative and conductive couplings.
A fourth objective of the present invention is to provide methods and systems to permit operation in previously unachievable realms of super highly concentrated solar irradiance.
A solar energy system with increased photovoltaic and thermal conversion efficiencies including a collection optics for receiving and concentrating incident sunlight, or radiation from any other directed electromagnetic energy source, an optical filtering unit for separating and redirecting infrared light and ultraviolet light from incoming solar light, a thermal distribution unit redirecting heat from the optical filtering unit into a thermal-loop, and a photovoltaic for receiving the filtered light from the filtering system and converting the light into electrical energy. The optical filtering unit can include an optical waveguide or an optical fiber selected from a group consisting of fiber, bundle of optical fibers, tapered rods, tapered fiber, photonic crystal fiber (PCF), multi-core, multi-clad, slab waveguides and hexagonal rod and can be a dielectric material or a glass material. Additionally, the optical waveguide uses one of a total internal reflection (TIR) and a transverse resonance to achieve electromagnetic confinement and guidance. The collection optics can be a Fresnel lens, a parabolic dish mirror, or a parabolic trough mirror and the entrance optics can be a window-filter, rod, tapered rod, multi-lens array, ball lens or lensed fiber. The filtering by the optical filtering unit is accomplished via at least one of the absorptive properties of the optics and the fiber, the chromatic aberration of the optics and the fiber, waveguiding and angle-tuning of the fiber to optimize the spectral transfer.
The thermal distribution unit redistributes heat by at least one of a conductive coupling of the heat to the thermal loop and a radiative coupling the heat from the optical filtering unit into the thermal loop. The optical fiber can be a fiber bundle of input heads that are epoxied together, a fiber bundles of input heads that are fused together, a fiber bundles of input heads having claddings removed and cores fused together or a metallic ferrule for housing the fiber bundle of input heads and a heat sink mesh between fibers in a bundle. The thermal distribution unit can also include a coolant with the optical fibers routed through the coolant and/or a heat pipe or heat pipes arrayed in a radial arm to a ring topology to rapidly transfer thermal energy collection optics into a manifold that interfaces the coolant flow to the rest of the thermal loop. The coolant, heat pipe or heat pipes arrayed in a radial arms to a ring topology are thermally insulated and can an evacuated glass tube.
The system can also include a frequency converter to convert a ultraviolet and a infrared radiation to a visible band that the photovoltaic is responsive to. In this example, the optical fibers in the bundle have claddings to form cladding pumped fiber amplifiers and can include a mirror and a fiber Bragg grating coupled to both ends of the optical fibers to form cladding pumped fiber lasers. The inner conduction tube can also form a single fiber amplifier with waveguiding of the amplifier providing a preferred direction for the re-radiation of the solar pumped molecules or atoms undergoing stimulated emission of radiation and a mirror at an ends of the inner conduction tube enhancing the direction for a stimulated emission, turning the amplifier into a laser. The laser is end pumped by one of a Fresnel lens and a dish mirror or side pumped by a trough mirror and grating at top of tube providing distributed feedback DFB eliminating mirrors at end of tube. The frequency conversion is resonantly enhanced in an optical resonator can be a fiber ring resonators incorporating couplers, a fiber ring resonators incorporating hybrid fiber/bulk-optics modules, a reflective resonators incorporating optical circulators and a fiber Bragg grating FBG and a mirror or a fiber based resonator.
In an embodiment, the collector includes a concentrated light beam source is one of an array of mirrors in a solar farm, a solar pumped lasers from one of a terrestrial, satellite, or platforms in the solar system, the collector receiving the concentrated light beam
Further objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments which are illustrated schematically in the accompanying drawings.